Well, I believe that they won't change the roster that much for SSB4, but they'll add in a few more attacks and more alternate costumes. Every character in Brawl has at least two alt costume choices, so why is Wario alone special?
My Dream Roster for SSB4:
The Marioverse team is fine - 7 of the Big 8 of Mario are represented, and Diddy is important in his own right (Diddy Kong Racing). Dr. Mario was superfluous in Melee, but could easily be adapted as an alt for Mario.
Zelda needs to get rid of Toon Link and replace him either with the REAL WW Link (with tools and skills from WW, MC and PH), Tingle (I don't see why everyone hates him, and he's the most important character before the Triforce Three), or a new character from the eventually-upcoming Zelda Wii. And they need to friggin' declone Ganondorf. If they use the Zelda Wii incarnation of Link as Link, they can give him the OoT and TP incarnations (from Melee and Brawl respectively) as alts, same with Zelda and Dorf.
Metroid needs another rep. Ridley, Sylux or Dark Samus would all work, though the latter two would probably be semi-clones of Samus. Zamus can stay, but get rid of the Final Smash transforming mechanic, and make her transformable like Zelda or PT. Samus has multiple alt possibilities, but most likely would be a "true" Fusion Suit.
All of the retro characters stay, but they could probably give ROB some better moves. As it stands now, the only thing ROB has that isn't original is his gyromite (down b). they could've incorporated Professor Hector in there, perhaps as an assist trophy or Final Smash. I've always imagined ICs having Balloon Fighter alt costumes, and Pit is fine as he is (though I wouldn't mind seeing an alt that's more true to his original form). G&W stays as he is.
Kirby series is fine. Olimar can stay, though he would probably be pretty close to the cut list if they were running out of dev time. Kirby would have a Waddle Dee alt, but I can't think of alts for Meta or D3.
Starfox characters? Either Wolf or Falco get cut, though it would be a close call; I think Falco innovates a bit more, but Wolf is a bit more important story-wise. If they had time, they could add Krystal, who we all thought would be a shoe-in (along with Ridley, Geno and Megaman), who would be a great deal more unique than Falco/Wolf.
Captain Falcon stays. If they had time, they could add in Samurai Goroh (with sword-based A moves and altered Falcon specials), or remix Ganondorf's moveset for use in a semi-clone Black Shadow or Blood Falcon.
For the Pokemon, Mewtwo comes back. They mix Melee Mewtwo and Brawl Lucario together, take the best of both movesets, and give it to Mewtwo with a Lucario alt. Maybe the Trainer would update his Pokemon to the Generation V starters, or they would just add another Trainer with that set. Jiggs would be close to getting deleted. Pichu would become a Pikachu alt.
FE keeps Marth and Ike, gets Roy back. Roy gets a fire projectile, a chargeable Counter with the same effect as Flare Blade (damages if charged too long) and better power and range than Marth (less than Ike), average speed, and a center sweetspot. Ike gets a Greil/Black Knight alt, Roy gets an Eliwood alt, Marth gets a Sigurd alt.
Mother is fine, though they could modify Ness or Lucas' moveset to add a few things they actually learned in-game (PK Rockin/Love as Final Smashes, maybe an Offense/Speed Up special). Ness gets a Paula alt, Lucas gets a Claus (Masked Man) alt.
Newcomers:
-As mentioned, Tingle, Ridley/Sylux/Dark Samus, Krystal, possibly a new Pokemon Trainer, possibly an F-Zero rep.
-Isaac from Golden Sun. If Golden Sun 3 is released, Isaac is all but guaranteed a spot in Brawl.
-If he actually appears in a canon Mario game, Waluigi could possibly take a roster spot. He has a number of random abilities (shiny eyes, swimming through invisible water, bombs, shadow thorns, etc) that would make a very random and unpredictable moveset. He could be the new joke character (again, assuming he does something of importance).
-Stafy is apparently one of Nintendo's upcoming franchises. If Brawl generates enough NA interest in Densetsu no Stafy, he could easily make the jump from assist to full-blown playable.
-Ray from Custom Robo. If you ever get a chance to play a Custom Robo game, it's a ton of fun, and again, Ray has a lot of moveset potential (as long as he was resized ala Kirby and Olimar)
-Someone to represent the "casual" side of Nintendo. Miis, Kawashima, Dr. Lobe... something like that. I'm not saying I want those characters specifically, but something to represent that.
-Smash is overdue for an original character. Whether it's someone like the Polygons/Wireframes/Alloys, or a story-based character like the Ancient Minister, I'm sure they could think of something.
Megaman is a must for new third-party characters. Sonic stays for sure, Snake might stay (but nerf him, for Master Hand's sake!). Three third-party characters is good, though Knuckles or Shadow could work if there's extra space.
I like the "Smash Meter" suggested by one of the previous posters. It's not exactly in the style of Smash to have a special bar, but there's potential. If they did go with it, the Smash Ball would just fill it up.
New Moves:
-B Tilts and Smashes: They could have the same general effect. A tilt special wouldn't be quite as powerful compared to a smash special, but you couldn't use smash specials in the air.
-Dash B: Likewise, some sort of special dash attack that grabs an opponent, pivots the character, short-range teleport, etc.
-Special Throw: Pressing B to execute a special throw - suicide toss, more powerful, etc.
-Dodge/Roll attacks: They wouldn't be that strong, but would do a bit of damage to repel enemies.
A better Story Mode is a must. Get it to incorporate actual Nintendo worlds and enemies. The Subspace Army could return, and a rematch with Tabuu is a must, but I would rather see other villains take the spotlight.
As for a name: Super Smash Bros. Rumble or Super Smash Bros. Burst. Super Smash Bros: Battle Royale (note the colon) would be better for a Smash 64 remake for the DS or something.
